Low
S.97 on Vaillant ecoTEC Plus 620

Your boiler is currently performing an internal health check on its sensors and has temporarily paused heating and hot water to ensure everything is functioning safely.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Automatic test programme: Water pressure sensor, heating and hot water request blocked.

Shared across the range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Wait for the boiler to complete its automatic test (this is normal operation)If the code persists for more than 15 minutes, press the reset buttonCheck the system pressure gauge is between 1.0 and 1.5 bar

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Related fault codes

All 170 fault codes on the ecoTEC Plus 620

Seeing a different code? Every code this model can display, in one place.

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